<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>防抖</title>
</head>

<body>
  <input type="text">
  <script>
    // 防抖：高频触发事件，只要执行最后一次事件处理函数
    const input = document.querySelector('input');

    input.oninput = debounce(function () {
      console.log(this.value);
    }, 500)

    // 封装防抖函数
    function debounce(fn, delay) {
      let timer = null;
      return function () {
        if (timer) {
          clearTimeout(timer)
        }
        timer = setTimeout(() => {
          // 业务代码,改变内部this指向
          fn.call(this)
        }, delay);
      }
    }
  </script>
</body>

</html>